How to save files into Downloads folder on iOS?

I am currently facing a problem, where I need to save a file (PDF) into downloads folder on iPhone (or in the best scenario prompt a download somehow) from Unity.

We can save data in Application.persistentDataPath, but that is, to my knowledge, inaccessible from the device itself.

Do you have any ideas, it will be something with the File class, but I do not know which path to put in there.